Backlight Unit Protrusion Patterns for Wide Viewing Angle
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Solution Overview
Problem
Conventional liquid crystal display devices with backlight units face limitations in achieving a wide viewing angle and thin, lightweight design, particularly when applied to devices like navigation systems, due to irregular light scattering and the need for additional optical sheets to adjust emission angles.
Innovation Solution
A backlight unit with a light guide plate featuring protrusion patterns formed by intersecting prisms, where the first prism is longer than the second, allows for enhanced light emission angles and improved luminance, enabling a wider viewing range without the need for additional diffusion sheets, thus facilitating a thinner and lighter design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional dot patterns are used on the light guide plate, then light scattering is improved, but burrs are generated causing irregular light scattering and requiring additional diffusion sheets
Solution Approach 1:
The dot pattern is segmented into two distinct components: a first dot pattern with larger diameter for primary light scattering, and a second dot pattern with smaller diameter for controlling burr effects. This segmentation allows each pattern to serve a specific function, preventing the burr-related problems while maintaining light scattering effectiveness.
Solution Approach 2:
Different regions of the light guide plate have different dot pattern configurations. The first dot pattern is positioned at specific locations for optimal light extraction, while the second dot pattern is strategically placed to address burr formation issues. Each local region has optimized properties suitable for its specific function.
2Ease of operation
If additional diffusion sheets are added to correct light scattering issues, then light emission angle control is improved, but device thickness and weight increase
Solution Approach 1:
The diffusion function is extracted from a separate diffusion sheet and integrated directly into the light guide plate through the dot pattern structures. This eliminates the need for an additional diffusion sheet layer, reducing overall device thickness while maintaining light emission angle control capabilities.
Solution Approach 2:
The light guide plate and diffusion function are merged into a single integrated component. The dot patterns on the light guide plate perform both light extraction and diffusion functions simultaneously, eliminating the need for separate diffusion sheets and reducing device complexity.
3Illumination intensity
If conventional dot patterns are used, then light extraction is improved, but viewing angle is limited due to irregular light scattering
Solution Approach 1:
The dot patterns exhibit asymmetric characteristics with the first dot pattern having a larger diameter than the second dot pattern. This asymmetry creates controlled light scattering patterns that improve viewing angle characteristics while maintaining effective light extraction from the light guide plate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively enlarges the viewing angle and enhances luminance, particularly at off-center positions, while maintaining a thin and lightweight structure, improving the liquid crystal display device's performance and cost-effectiveness for applications requiring wider viewing angles.
Implementation Method 1
The light guide plate 12 guides incident light supplied from the light source 11, and emits light upon a light emitting surface (an upper surface of the light guide plate 12 illustrated in FIG. 1A) facing the liquid crystal panel 20. The light emitted from the light guide plate 12 has an incident angle which is equal to or less than a critical angle.
Implementation Method 2
Since light is diffused and scattered on the plurality of dot patterns 12b, the incident angle of light reached the light emitting surface 12a may be changed and thus more light has the incident angle being equal to or less than a critical angle.
Implementation Method 3
The prism sheet 14 concentrates light.
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
Disclosed herein is a backlight unit (100) in which a viewing angle of a liquid crystal display device may be easily enlarged or changed. The backlight unit (100) includes a light source (110), a light guide plate (120) formed below a liquid crystal panel (200) and including a light emitting surface through which incident light supplied from the light source (110) is emitted toward the liquid crystal panel (200), a prism sheet (130) formed between the light guide plate (120) and the liquid crystal panel (200), and a plurality of protrusion patterns (150) formed on one surface of the light guide plate (120) which is opposite to the light emitting surface thereof, each of the plurality of protrusion patterns (150) including a first prism (151) which extends in a first direction and at least one second prism (152) which extends in a second direction intersecting with the first direction, comes into contact with the first prism (151), and is shorter than the first prism (151).